Manufacture of rubber



Patented May 19, 1925.

UNITED STATES PATENT OFFICE.

PHILIP SCHIDROWITZ, WILLIAM FELDENHEIMER, AND WALTER WILLIAM PLOW- MAN,OF LONDON, ENGLAND.

MANUFACTURE OF RUBBER.

N'o Drawing. Original application filed May 13, 1920, Serial No.381,179. Divided and filed September 3, 1921.

7 '0 all whom it may concern:

Be it known that we, Dr. PHILIP SoHIDno- \vrrz, lViLLiAM FELDENHEIMER,and 'WALTER WILLIAM PLowMAN, all subjects of the King of England, andall residing in London, England, have invented certain new and usefulImprovements in the Manufacture of Rubber, of which the following is aspecification.

This invention is for improvements in or relating to the manufacture ofrubber.

Various substances have been used for incorporation in rubber mixings toact as fillers and for other purposes, and among such substanceschina-clay has been employed. In U. S. specifications, Serial Nos381,179 filed May 13, 1920, and 416,528 filed October 12, 1920, aprocess for the treatment of clay is described and it has been foundthat if this clay be added to rubber, the resulting rubber-mixture isimproved in various ways, for example, it cures more rapidly, thebreaking strain of the product and the toughness, and distensibility ofthe latter are increased; moreover, the degree of increase of certain ofthese qualities can be varied according to the particular treatment.

of the clay.

The clay, which is preferably a purified clay, is prepared by firstsuspending it in water with the aid of a deflocculator, and then dryingthe clay while in the deflocculated state.

The clay may be first mixed with an equal weight of water which willrender it a pasty mass, and then a deflocculator added in sulficientquantity to produce fluidity, with or without increasing this additionof a deflocculator until the fluidity first produced decreases, oradding the water with the deflocculator in sufficient proportion tobring about this last condition in one operation, and then drying theclay whilst in this state, with or without first running off anysupernatant liquor or a part thereof. Obviously the less water used inpreparing the clay, the less there is to evaporate ofi' afterwards andit will be found that if sufficient water is added to bring the clay toa pasty condition, this is usually enough for carryingout the processand represents approximately the minimum quantity of water which can beused.

In certain cases the clay is purified by this application Serial No.498,450.

making a suspension of it in water with a deflocculator and then addinga flocculator prior to treating it as above described with or withoutintermediate drying.

Heretofore, clay for mixing with rubber has been prepared-merely bypassing it over. the mica-drags in thewell-known manner. \V e have alsoprepared clay for mixing with rubber by making a suspension of it inwater witha defiocculator and then throwing it down by the aid of areagent, running off the liquor and drying it, but it is found that themarkedly different qualities referred to above as produced in the rubberby the addition of clay when it is dried whilst in the deflocculatedstate, are not obtainable when the drying is effected after flocculationafter the immediately preceding operation, although this last'materialhas special properties superior to untreated clay for rubber mlxes.

It is found that by the incorporation in a rubber mixing of china-claypreparedaccording to-the process set forth above, a

degree of toughness, strength, distensibility, curing capacity, andspecific gravity, can be obtained which heretofore, if obtainable atall, has only been obtained by the introduction of a number ofingredients into the mixing. The use of a number of ingredients as inthe methods at present adopted for the manufacture of rubber is complexin working, and costly if results such as are obtainable by the use ofclay prepared according to this process "are aimed at.

According to one method of carrying out thisinvention as applied to anormally settling clay, such as Fraddon china-clay, mined from FraddonDown, Cornwall, the clay is first washed, by a known process cons'istingin passing it over mica drags in the usual manner, but instead of usingwater only, a solution of 1.2 parts by weight of actual sodium-carbonate(100 per cent) in 2000 parts by weight of water is employed for, 100parts, or 5 per cent by weight of clay, that is to say, a 5 per centsuspension. This carbonate solution causes a greater quantity of mica tobe deposited on the drags than is the case when water only is employed,and the solution, with the clay in suspension in it, is then passed onto a settling-tank where it is left long enough, say 4 hours, forfurther deposition of the mica co I From this tank, the solution withthe clay in it is run into a depositing tank where a weak solution ofcommercial alum is added, in quantity sufficient approximately toneutralize the alkalinity of the solution to deposit the clay, as iscommonly done with clay emulsions. If desired, the deflocculator, thatis the sodium carbonate, may be added to the sus-' pension when it is inthe tank and not whilst it is running over the mica-drags, and afterbeing allowed to stand therein for about A hours, which is notsuflieient to allow a deposition of clay to occur, it may be run offinto a second tank where the fiocculator, that isthe alum solution isadded and such flocculating reagent is added slowly enough, or in suchtotal quantity relatively to the quantity of the defiocculator asto'cause oc- *culation or coa lation of the clay, but not rapid sedimenttion. p

The process thus far described, isonly a means of obtaining a pure clay,and that part of the process to which the present iiivention relates,consists, according tothis example, in deflocculating the clay, soprocuredby thoroughly mixing the same with an equal weight of Water inthe presence-of 3% of anhydrous sodium carbonate by weight relatively tothe weight of the water. The water is then evaporated offwithout theaddition of any other reagent and the dry clay so obtained is ready forincorporation with the rubber. The clay particles produced in thismanner will have sodium carbonate adsorbed upon them in quantity up tosubstantially 3% of anhydrous sodium carbonate relatively to the clay.

I The amount of deflocculator can be gauged if desired by mixing theclay with an equal weight of water, which will render it pasty, and thenadding just suiticient defiocculating material to make it fluid.

The clay prepared with this amount of defiocculator will to some extentimprove therubber-mixture as has already been described, but if it isdesired to enhance still further the various properties mentioned, or toenhance some in a greater proportion to others, then the proportion ofthe deflocculator can be increased until the clay begins to againthicken. In actual practice, of course, the amount of deflocculatornecessary for this purpose can be ascertained on a sample, and then thewhole of the deflocculator which is to be used can be added in oneoperation with the water when making the suspension.

The term deflocculating reagent or deflocculator, as employed in thisspecification and the claims, is to be understood as restricted to thattype of reagent which reduces the size of the particles of the materialtreated, in contradistinction'to those reagents (of which tannin is anotable exto be used,

ample) whose action is that of protective colloids and which do notthemselves reduce the size of the particles of the material. Likewisethe term deflocculation, as used herein, is to be interpreted asappertaining to the eflec't produced by reagents of the former typealone, while the term deflocculated as used herein means that thematerial so qualified by this term is in that condition of dispersionproduced by the action of a defioccula'tor. Thus, an initiallydeflocculated clay means a clay which, at one stage or another of itspreparation, has been subjected to a deflocculation process.

It has been found with Fraddon clay prepared according to the knownprocesses; previously described, that if say, to 1% of sodium carbonate,for example the ordinary qualityknown as soda ash, be employedrelatively to the weight of water (distilled), the clay thus treated isdried and when added to a rubber-mixing will a rubber-mixing suitablefol- Parts.

Rubber 228 Sulphur 12 The dried clay 16O The mixing is worked up in theusual mannor and finally vulcanized, for example by steam at 40 lbs.pressure for to 3 hours according to the character of the preparation.

Instead of soda-carbonate, other detlocculators could be used, such asammonia.

Although cliina-clay-has been referredto throughout this specification,itwvill be understood that this term is used to cover any clay havingsimilar properties though perhaps not generally known. as a chinaclay.

This application is a application Serial No. 1920. j v

What we claim as our invention and desire to secure by Letters Patent isdivision of our prior" 381,179 tiled May 13,,

- 1. In the manufacture of rubber con'ipo-Y,

sitions, the steps consisting in incorporating with the vulcanizablerubber mixing a dry clay. which has been subjected ,to deflocculationand then vulcanizing the mixing.

2. In the manufacture of rubber eompojsi tions, the steps consisting inincorporating with the vulcanizable rubber mixing dry clay which hasbeen initially deflocculated with an inorganic-defiocculator, and thenvulcanizing the mixing.

3. In the manufacture of rubber c'ompositions, the steps consisting inincorporating with a vulcanizable rubber mixing dry clay which hasbeendefiocculated with a basic reagent and then vulcanizing the mixing.

4. In the manufacture of rubber compositions, the steps consisting inincorporating with a vulcanizable; mixing dry clay whichhas been'deflocculated with an alkali and then vulcanizing th mixing.

5. In the manufacture of rubber compositions, the steps consisting inincorporating with a vulcanizable rubber mixing dry clay which has beendefiocculated with sodium carbonate and then vulcanizing the mixing.

6. In the manufacture of rubber compositions, the steps consisting inincorporating with a'vulcanizable rubber mixing purified clay which hasbeen initially deflocculated with an inorganic deflocculator and driedand then vulcaniz'ing the mixing. 7. In the manufacture of rubbercompositions, the steps consisting in incorporating with a vulcanizablerubber mixing the product obtained by defiocculating clay with anaqueous'alkaline reagent and evaporating the clay suspension to dryness;and then vul- .tanlzing t-ne mixing.v

tions, the steps consisting in incorporating with a vulcanizable rubbermixing the product obtained by deflocculating clay with aqueous sodiumcarbonate and evaporating the clay suspension todryness and thenvulcanizing the mixture.

10. In the manufacture of rubber compositions, the steps consisting inincorporating with the vulcanizable rubber mixing initially.deflocculated dry clay having adsorbed upon it an inorganicdeflocculator in substantially the proportion requisite fordeflocculating the clay.

11. A vulcanized rubber composition containing clay -which prior toaddition to the rubber mixing has been dried while in the defioceulatedstate. f

12. A vulcanized rubber composition containing clay which prior toaddition to the rubber mixirig has been deflocculated by aid ofsufficient alkaline defiocculator to bring about incipient fi'occulationand dried While in the said state. a

13. A vulcanized rubber composition containing clay of particles of thereduced dimensions produced by a defiocculation treatment of the clay,said particles having adsorbed upon them an inorganic defloccu- I lator.

15. A vulcanized rubber composition containing clay of particles of thereduced dimensions produced by a. defiocculation treatment of the clay,said particles having an alkali adsorbed upon them.

16. A vulcanized rubber cqmposition containing clay of particles of thereduced dimensions produced by a defiocculation treatment of th clay,said particles having sodium carbonate adsorbed upon them.

17. A vulcanized rubber composition containing clay of particles of thereduced dimensions produced by a defiocculation treatment andsubstantially free from non-defiocculable impurities of clay.

18. A vulcanized. rubber composition containing clay of particles of thereduced dimensions produced by a defiocculation treatment of theclay andsubstantially free from non-deflocculable impurities ofclay, said clayparticles having an alkali adsorbed upon them. 19. A vulcanized ILlbbGICOlhPOSltlOll containing clayof? particles of the reduced di= mensionsproduced by a defiocculation treat ment of the clay and substantiallyfree from non -deflocculable impurities of clay, said clay particles vhaving sodium carbonate adsorbed upon them in quantity up tosubstantially 3% of anhydrous sodium carbonate relatively to the clay.

22. A vulcanized rubber composition containing clay which, prior toaddition to the rubber mixing, has been dried in the deflocculatedstate, the particles of said clay having an inorganic deflocciilatoradsorbed upon them.

' 23. A vulcanized rubber composition containing clay which, prior toaddition to the rubber mixing, has been dried While in the deflocculated state, the particles of said clay having an inorganicdeflocculator adsorbed upon them in quantity substantially within ,theproportions requisite for deflocculating inorganic deflocculator anddried while in p the deflocculated state.

25. A rubber composition containing clay which, prior to addition to therubber mixing, has been purified by a deflocculation process with aninorganic deflocculator,'redeflocculated and dried while in this state.

26. A rubber composition containing clay which, prior to addition to therubber mixing, has been purified by a deflocculation process,redeflocculated by aid of an alkaline deflocculator, and dried while inthe deflocculated state.' I

27. A rubber composition containing clay which, prior to addition to therubber mixing, has been purified by a deflocculation process,redeflocculated by aid of sodium carbonate, and dried While in thedefloccu.

lated state.

28. A rubber compostion containing clay, which prior to addition to therubber mixing, has been purified by a deflocculation process,flocculated, redeflocculated by aid of an alkaline defloceulator, anddried while in the deflocculated state.

29. A rubber composition containing clay which, prior-to addition tothe. rubber mixing, has been deflocculated by aid of sulficient alkalinedeflocculator to bring about incipient gelation and dried while in theso deflocculated state.

30. In the manufacture of rubber compo- .state, adding the clay to avulcanizable rub.-

ber mixing and .then vulcanizing the mixing.

32. In the manufacture of rubber compositions, the steps consisting indeflocculating a clay, adding such deflocculated clay to a vulcanizablerubber mixing and then vulcanizing the mixing. w

33. In the manufacture of rubber compositions, the steps consisting inincorporating with the vulcanizable rubber mixing the product obtainedby defiocculating clay and evaporating the clay suspension to drynessand then vulcanizing the mixing.

34. A vulcanized rubber composition containing an initiallydeflocculated clay.

35. In the manufacture of rubber compositions, the steps consisting indefiocculating a clay, adding the clay to a vulcanizable rubber mixingand then vulcanizing the mixing.

PHILIP SCHIDROWI-TZ. WILLIAM FELDENHEIMER. WALTER WILLIAM PLOWMAN.

